A fourth man - a citizen of United Arab Emirates - is accused of supporting the men in carrying out surveillance on a host of potential targets prior to the co-ordinated attacks, which left about 3,000 people dead.

According to the memo quoted by The Telegraph, the three Qatari citizens carried out surveillance at the World Trade Center, the Statue of Liberty, the White House and in Virginia, the state where Pentagon and CIA headquarters are located.

The cable says the men flew into New York from London three weeks before September 11, 2001.

Ten days later, they flew to Los Angeles and checked into a hotel close to the airport. They were to check out on September 10 and were booked on an American Airlines flight from Los Angeles to Washington, but failed to board the flight.

The following day, the same aircraft, flying on route AA77, was hijacked and crashed into the Pentagon.

The three suspects reportedly flew back to London before returning to Qatar. Their present location is unknown.